Fluorescent hybridization probes have developed into an important tool in the sequence-specific detection of DNA and RNA. The signals generated by the appended fluorescent labels (or dyes) can be monitored in real time and provide simple, rapid, and robust methods for the detection of biological targets and events. Utility has been seen in applications ranging from microarrays and real time PCR to fluorescence in situ hybridization (FISH).
Recent work in the area of multichromophores, particularly regarding conjugated polymers (CPs) has highlighted the potential these materials have in significantly improving the detection sensitivity of such methods (Liu and Bazan, Chem. Mater., 2004). The light harvesting structures of these materials can be made water soluble and adapted to amplify the fluorescent output of various probe labels (See U.S. patent application Ser. No. 10/600,286, filed Jun. 20, 2003 and Gaylord, Heeger, and Bazan, Proc. Natl. Acad. Sci., 2002, both of which are incorporated herein by reference in their entirety).
Results such as these indicate CPs to be highly promising in the field of nucleic acid diagnostics, particularly where sample quantities are scarce. However, there exist methods for the amplification (or replication) of nucleic acid targets, i.e., PCR. Comparatively, in the field of protein recognition, there are no such simple methods for amplifying the targeted materials. As such, signal enhancement arising from CP application is of high consequence in this area.
Dye-labeled antibodies are regularly used for the detection of protein targets in applications such as immunohistochemistry, protein arrays, ELISA tests, and flow cytometry. Integrating CP materials into such methodologies promises to provide a dramatic boost in the performance of such assays, enabling detection levels previously unattainable with conventional fluorescent reporters (e.g., dyes).
Beyond addition signal, one of the other key drivers in biological detection formats is the ability to detect multiple analytes in the same test or multiplexing. This is commonly achieved by using fluorescent reporters with operate at different, discernable wavelengths. CP materials are ideally suited to provide a platform for expanded multiplexing. This can be achieved by tuning the structure of different CPs to operate at different wavelengths or by incorporating a dye within the polymer-biomolecule conjugate.
The material and methods to produce higher sensitivity biological assays and increase multiplexing are highly desired in both molecular (nucleic acid) and immunoassay formats.